The present invention relates generally to dielectric resonator devices and more specifically to dielectric resonator devices in which a dielectric resonator element is mounted inside a cavity.
Dielectric resonator devices in which a dielectric resonator element is mounted inside a cavity are well known in the art. Such resonator devices should ideally have the dielectric resonator element levitated in the center of the surrounding cavity with absolute precision and rigidity.
Idealism aside, many mounting methods have been used to approximate such a geometry with varying degrees of success. Generally, these methods suffer from thermal instabilities, overheating or dimensional shifting, or from resonant degradation wherein the support structure affects the frequency or the quality factor, Q.
In U.S. Pat. No. 5,097,238 to M. Sato et al there is disclosed a cavity type dielectric resonator device comprising a dielectric resonator body of dielectric ceramic having a resonator portion, a supporting portion and a mounting flange portion, the mounting flange portion being on the lower end of the supporting portion, a base member for mounting the dielectric resonator body, and fastening members for removably fixing the mounting flange on the base member, wherein the resonator portion and the mounting flange portion are integrally formed, the mounting flange portion of the resonator body and the base member have bores through which said fastening members are fastened, and the fastening members comprise bolts and nuts of dielectric ceramic material.
Also disclosed in U.S. Pat. No. 5,097,238 to M. Sato et al is a cavity type dielectric resonator device which includes a dielectric resonator element, a metal casing and an insulating holder made of alumina or forsterite. The dielectric resonator element is mounted on the upper portion of insulating holder and secured thereto by an adhesive layer while the lower portion of the insulating holder is secured to an annular metal flange by an adhesive layer. The annular metal flange is secured to the metal casing by bolts and nuts.
In U.S. Pat. No. 5,111,170 to K. Ohya there is disclosed a cavity type dielectric resonator device comprising a dielectric resonator body of dielectric ceramics having an inner bore provided along the axis thereof, a pedestal having an inner bore provided along the axis thereof, a shield casing for containing the resonator body and the pedestal, and a fastening member inserted into the inner bores of the resonator body and the pedestal for fastening and fixing them on the base wall of the shield casing, wherein the shield casing and the fastening member are provided with openings for circulating a cooling gas in the shield casing, respectively. In one version of the device the resonator body and pedestal are separate members while in another version of the device the resonator body and pedestal are a unitary structure.
Also disclosed in U.S. Pat. No. 5,111,170 to K. Ohya is a cavity type resonator device which includes an annular shaped resonator element, an annular shaped support and a bolt and nut for holding the resonator element down on the support and the support on the base wall of a shield casing. In addition, there is disclosed a cavity type resonator device which includes a base wall, a support secured to the base wall by an adhesive member and a resonator element secured to the support by an adhesive member.
Other known U.S. patents of interest include U.S. Pat. No. 4,121,181 to T. Nishikawa etc., U.S. Pat. No. 4,136,320 to T. Nishikawa etc, and U.S. Pat. No. 4,620,168 to X. Delestre et al.
It is an object of this invention to provide a cavity type dielectric resonator device which includes an arrangement for mounting the dielectric resonator element inside the cavity using low loss materials in a mechanically stable configuration.